Preaching the gospel of spiritual independence

May 31, 2010

Reality is real, but brains construct knowledge

When Amazon delivered Paul Thagard's "The Brain and the Meaning of Life," I knew I was going to enjoy the book after I perused some chapter titles -- the first four being We All Need Wisdom, Evidence Beats Faith, Minds are Brains, and How Brains Know Reality.

Ah, inspiration for my churchless non-soul.

I'm one chapter away from finishing the book. Probably I'll write another post about it after I read Making Sense of It All. (I can only hope; that's a pretty confident claim for a chapter.)

Here I'll focus on some key concepts in How Brains Know Reality. This subject naturally is interesting to me, along with everyone else, since obviously we all have brains that are engaged in knowing reality.

Once in a while on this blog I get a comment from someone who questions whether this is possible. Specifically, whether the scientific method is any better than mysticism or religion as a means for understanding what the cosmos is all about.

This attitude surprises me.

After all, that person is using a computer to access the Internet so he or she can express an opinion that science is useless. Huh? A whole lot of scientific knowledge is backing up the technology that made it possible for someone to say, "It isn't possible to know reality by means of science."

I also hear from people who seem to believe that direct experience through some sort of "pure awareness" is the sine qua nonof genuine knowledge. This notion also surprises me, given what is known about the many unconscious processes in the human brain.

Thagard's approach to knowing reality makes much more sense to me.

I think that lions and mountains are real, and so are clouds and electrons. But the hypothesis that minds are brains does not support a kind of naive realism according to which things are just as we perceive or conceive them to be. We know enough about how brains work to show that both perceiving and theorizing are highly constructive processes involving complex inferences.

Nevertheless, there are good reasons to believe that, when the brain is working well, it achieves knowledge about the reality of both everyday objects like mountains and theoretical scientific entities like electrons. This chapter shows how brain science and philosophical reflection together support a kind of constructive realism, the view that reality exists independent of minds, but that our knowledge of it is constructed by brain processes.

Hard to argue with.

When we go on our evening walk, my dog has a very different experience of reality than I do, given her vastly superior sense of smell. As I stand holding the leash, waiting for her to finish a comprehensive sniffing of a clump of grass that looks to me just like all the other clumps along the road, she is engaged in tasting an odor feast that's beyond my comprehension.

So we Homo sapiens do indeed construct our knowledge of reality through the only means available to us: the human brain. Thagard reviews some hypotheses about how we do this, and arrives at a favored theory: inference to the best explanation.

Don't be thrown off by this fancy phrase.

It's what we all do every day of our lives. Recently my wife excitedly told me that I had to come and see what was being done to a cherished twenty year old vine maple tree that is a centerpiece of our landscaping.

Bark was being chewed off. Not just a little. A lot. Some large branches were almost girdled, which could kill them. We talked about what animal could be the culprit. Deer? Raccoons? Ground squirrels?

We immediately suspected the latter, as they've been causing us other problems.

Some Googling revealed that they do indeed like to eat bark, something we hadn't noticed before. So ground squirrels became our inference to the best explanation and we've been acting accordingly to deal with the little furry irritants.

Thagard says:

Inference to the best explanation in science has the same basic structure as does reasoning in law, medicine, and everyday life. In all these domains, you should collect as much relevant evidence as you can, consider higher-level hypotheses and alternative ones, and accept the ones that provide the best overall explanation of the evidence.

This evidence doesn't have to be only direct perceptions.

In science and in everyday life, many of our concepts go beyond sensory experience. For example, our talk about the minds of other people frequently refer to their beliefs, wants, and emotions even though we cannot directly experience them. Scientific theories evoke many kinds of entities that cannot be directly observed -- among them, atoms, electrons, quarks, black holes, genes, biochemical pathways, viruses, personalities, and mental representations.

Our knowledge of the world would be desperately limited if we had to follow the injunction of strict empiricists that our knowledge be confined to what human senses can experience. Other animals have superior senses: birds can see ultraviolet light, dogs have more sensitive noses, bats can use echolocation, and so on.

The particular range of sensory experience open to humans is a coincidence of biological evolution, not a perfect guide to the nature of reality. Where humans far exceed other animals is in our ability to construct and evaluate brain representations that transcend our sensory limitations.

Problem is, some of these brain representations don't correspond to any sort of meaningful demonstrable reality.

Like unicorn, angel, god, and soul. Scientific theories aren't immune from this. Thagard notes that the concept of phlogiston once was used to explain combustion. Now we know better.

So some scientific skeptics argue that everything science currently knows through its inferences to the best explanations will be overturned one day. Thagard disagrees.

I don't know of a single broadened and deepened scientific theory that has turned out to be false. Of course, inference to the best explanation and any other kind of evidence-based thinking is fallible. There is always the possibility that new evidence will be gathered or new hypotheses will be generated showing that our current ideas are wrong... Concepts such as electron and gene that go well beyond sensory experience can nevertheless be judged to refer to real objects, as long as they are parts of theories that provide the best explanation of the available evidence.

OK, this makes sense for "real objects." But how about what can loosely be called "meaning of life objects"? In other words, goals, desires, intentions, longings, and such that aren't objectively real to others, but are definitely subjectively real for us.

Thagard talks a lot about the meaning of life in other parts of his book -- too big a subject for this blog post. I liked how he showed that inference to the best explanation works well for personal/meaning issues, just as it does for universal/knowledge issues.

Our brains construct reality when we infer what is true about the world using the scientific method summarized above. Likewise, we construct a meaningful life when we infer how best to achieve our goals using similar sorts of methods.

Distinguishing these separate sorts of constructions is important, though. Thagard, in my opinion, doesn't focus enough on this (maybe he will in the final chapter that I haven't read yet).

As I often say on this blog, I've got no problem with people being attracted to whatever wild and crazy religious, spiritual, mystical, or philosophical beliefs they find useful in fulfilling their meaning of life goals.

Just don't expect me to believe like you. Or expect social policies to reflect your concepts without offering up some good reasons beyond "just have faith."

I also have no problem with people being attracted to whatever sorts of sexual activities turn them on (so long as children, or other innocents, aren't harmed). Nor do I have a problem with people being attracted to all sorts of artistic, musical, literary, athletic, culinary, and other pursuits.

Browsing an art gallery, my wife and I often say, "Jeez, who would want to buy that?" Well, the person at the cash register who we notice paying for the item as we walk out the door. Vive le difference.

We need to respect personal choices, whether they be religious, sexual, artistic, philosophical, or whatever. This is a big part of what makes life so interesting: variety.

I used to belong to the downtown Salem Rotary Club. For a number of years I enjoyed going to the weekly lunch meetings where a speaker would hold forth on some subject that interested him or her (some day I'll put up a post about my own "Quantum Barbie" talk, where I used a doll to illustrate principles of quantum physics).

I distinctly remember a guy who was into a Civil War battle, Pickett's Charge, big time. I mean, really big time. He seemed to know everything about it. I was mesmerized by how enthusiastic the guy was as he shared high points about his obsession in a 20 minute presentation.

It struck me as akin to a work of art created with tremendous passion. Myself, I couldn't care less about Pickett's Charge. But I enjoyed the guy's enjoyment (through mirror neurons, probably, another subject Thagard talks about quite a bit).

So it's possible to come to a consensus about the "outside" reality that we all share. This is a marvelous accomplishment of the scientific method, using the inference to the best explanation approach.

However, when it comes to constructing a meaningful life, people are always going to differ about what is most important, valuable, and worthy of being pursued.